Unified Inch (UNC / UNF / UN)
UNC Unified Coarse Thread
The standard inch thread for general-purpose fasteners in North America, e.g. 1/4"-20 UNC, 3/8"-16 UNC.
- Standard
- ANSI/ASME B1.1
- Flank angle
- 60°
- Sizes listed
- 33
- Range
- #1 - 64 UNC – 4" - 4 UNC
| Nominal Diameter | Major Diameter Inch | Major Diameter mm | Tapping Drill Size mm | TPI | Pitch mm |
|---|---|---|---|---|---|
| #1 - 64 UNC | 0.073 | 1.854 | 1.50 | 64 | 0.397 |
| #2 - 56 UNC | 0.086 | 2.184 | 1.78 | 56 | 0.453 |
| #3 - 48 UNC | 0.099 | 2.515 | 2.05 | 48 | 0.529 |
| #4 - 40 UNC | 0.112 | 2.845 | 2.27 | 40 | 0.635 |
| #5 - 40 UNC | 0.125 | 3.175 | 2.59 | 40 | 0.635 |
| #6 - 32 UNC | 0.138 | 3.505 | 2.77 | 32 | 0.794 |
| #8 - 32 UNC | 0.164 | 4.166 | 3.42 | 32 | 0.794 |
| #10 - 24 UNC | 0.190 | 4.826 | 3.82 | 24 | 1.058 |
| #12 - 24 UNC | 0.216 | 5.486 | 4.47 | 24 | 1.058 |
| 1/4" - 20 UNC | 0.250 | 6.350 | 5.11 | 20 | 1.270 |
| 5/16" - 18 UNC | 0.313 | 7.938 | 6.55 | 18 | 1.411 |
| 3/8" - 16 UNC | 0.375 | 9.525 | 7.95 | 16 | 1.587 |
| 7/16" - 14 UNC | 0.438 | 11.112 | 9.30 | 14 | 1.814 |
| 1/2" - 13 UNC | 0.500 | 12.700 | 10.73 | 13 | 1.954 |
| 9/16" - 12 UNC | 0.563 | 14.288 | 12.15 | 12 | 2.117 |
| 5/8" - 11 UNC | 0.625 | 15.875 | 13.53 | 11 | 2.309 |
| 3/4" - 10 UNC | 0.750 | 19.050 | 16.46 | 10 | 2.540 |
| 7/8" - 9 UNC | 0.875 | 22.225 | 19.34 | 9 | 2.822 |
| 1" - 8 UNC | 1.000 | 25.400 | 22.15 | 8 | 3.175 |
| 1 1/8" - 7 UNC | 1.125 | 28.575 | 24.87 | 7 | 3.628 |
| 1 1/4" - 7 UNC | 1.250 | 31.750 | 28.05 | 7 | 3.628 |
| 1 3/8" - 6 UNC | 1.375 | 34.925 | 30.60 | 6 | 4.233 |
| 1 1/2" - 6 UNC | 1.500 | 38.100 | 33.70 | 6 | 4.233 |
| 1 3/4" - 5 UNC | 1.750 | 44.450 | 39.26 | 5 | 5.080 |
| 2" - 4 1/2 UNC | 2.000 | 50.800 | 45.03 | 4.5 | 5.644 |
| 2 1/4" - 4 1/2 UNC | 2.250 | 57.150 | 51.38 | 4.5 | 5.644 |
| 2 1/2" - 4 UNC | 2.500 | 63.500 | 57.00 | 4 | 6.350 |
| 2 3/4" - 4 UNC | 2.750 | 69.850 | 63.36 | 4 | 6.350 |
| 3" - 4 UNC | 3.000 | 76.200 | 69.71 | 4 | 6.350 |
| 3 1/4" - 4 UNC | 3.250 | 82.550 | 76.06 | 4 | 6.350 |
| 3 1/2" - 4 UNC | 3.500 | 88.900 | 82.41 | 4 | 6.350 |
| 3 3/4" - 4 UNC | 3.750 | 95.250 | 88.76 | 4 | 6.350 |
| 4" - 4 UNC | 4.000 | 101.600 | 95.11 | 4 | 6.350 |
Reference values only. Verify against the current edition of the governing standard before use in production drawings or manufacturing. Provided by Micro Components as a free engineering resource.